And we see that file is first and proxy comes somewhat later. This means that in the example
above all queries are routed to the file plugin. It will happily answer those with SERVFAIL,
because it probably can’t find www.google.com in a file that will mostly have *.example.com
names in it.

In order to fix this, we should either have to separate stanza or specify the origin(s) for the
file plugin:

. {
proxy . 8.8.8.8:53
file db.example.com example.com
}

To preempt a feature request: Yes, it would be nice of CoreDNS can detect and warn about this (it
does not do this now).